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Intermolecular Interaction of Actin Revealed by a Dynamic Light Scattering Technique

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journal contribution
posted on 16.02.2006 by Noriko Kanzaki, Taro Q. P. Uyeda, Kazuo Onuma
The intermolecular interaction force of actin was studied by a dynamic light scattering technique. The mutual diffusion coefficients (D) of monomeric actin were accurately determined in a G-buffer with a low concentration of KCl from 0 to 10 mM. The translational diffusion coefficient was obtained as D0 = (87 ± 3) × 10-12 m2·s-1 at 25 °C and pH 7.4, which gives a hydrodynamic radius of monomeric actin of rH = 2.8 ± 0.1 nm. The Derjaguin−Landau−Verwey−Overbeek (DLVO) theory, assuming electrostatic and van der Waals potentials, failed to describe the change in interaction parameter (λ) with KCl concentration, but the extended DLVO theory succeeded if an additional repulsive potential was assumed. The Hamaker constant of actin in the Ca2+−ATP bound state was determined for the first time as AH = 10.4 ± 0.6 kBT.